U.S. patent application number 17/083327 was filed with the patent office on 2021-05-27 for sensor element for storing rotation or position information.
The applicant listed for this patent is DR. JOHANNES HEIDENHAIN GmbH. Invention is credited to Martin Heumann, Wolfgang Holzapfel, Johannes Schneider.
Application Number | 20210156662 17/083327 |
Document ID | / |
Family ID | 1000005220772 |
Filed Date | 2021-05-27 |
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United States Patent
Application |
20210156662 |
Kind Code |
A1 |
Schneider; Johannes ; et
al. |
May 27, 2021 |
SENSOR ELEMENT FOR STORING ROTATION OR POSITION INFORMATION
Abstract
A sensor element for storing rotation or position information
includes a substrate and a domain wall conductor arranged on the
substrate. A course of the domain wall conductor is of a closed
circumferential, continuous configuration without crossings. The
domain wall conductor comprises a first region having a positive
curvature and a second region having a negative curvature.
Inventors: |
Schneider; Johannes;
(Traunstein, DE) ; Holzapfel; Wolfgang; (Obing,
DE) ; Heumann; Martin; (Traunstein, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DR. JOHANNES HEIDENHAIN GmbH |
Traunreut |
|
DE |
|
|
Family ID: |
1000005220772 |
Appl. No.: |
17/083327 |
Filed: |
October 29, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01B 5/24 20130101; B82Y
25/00 20130101 |
International
Class: |
G01B 5/24 20060101
G01B005/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2019 |
DE |
10 2019 218 351.4 |
Claims
1. A sensor element for storing rotation or position information,
the sensor element comprising: a substrate; and a domain wall
conductor arranged on the substrate, a course of the domain wall
conductor being of a closed circumferential, continuous
configuration without crossings, and the domain wall conductor
comprising a first region having a positive curvature and a second
region having a negative curvature.
2. The sensor element according to claim 1, wherein the domain wall
conductor is configured as a conductor track on the substrate.
3. The sensor element according to claim 1, wherein a width of the
domain wall conductor is less than 1000 nm.
4. The sensor element according to claim 1, wherein the substrate
comprises a glass layer and/or a silicon layer.
5. The sensor element according to claim 1, further comprising
read-out elements by which a local magnetization state of the
domain wall conductor is determinable.
6. The sensor element according to claim 5, wherein the domain wall
conductor (is arranged in a layer between at least one of the
read-out elements and the substrate.
7. The sensor element according to claim 5, wherein at least one of
the read-out elements is arranged in a layer between the substrate
and the domain wall conductor.
8. The sensor element according to claim 5, wherein the read-out
elements are configured as giant magnetoresistance (GMR) or tunnel
magnetoresistance (TMR) sensors.
9. The sensor element according to claim 1, wherein the sensor
element has a plurality of domain wall conductors which have
different numbers of first regions or different numbers of second
regions.
10. The sensor element according to claim 9, wherein the different
numbers of first regions are coprime.
11. A storage system comprising the sensor element according to
claim 5 and a magnet arrangement which is movable in a first
direction relative to the domain wall conductor.
12. The storage system according to claim 11, wherein the magnet
arrangement is configured as a magnet array comprising magnets
having poles that are arranged offset from each other in the first
direction.
13. The storage system according to claim 11, wherein the magnet
array comprises magnets having poles that are arranged offset from
each other in a second direction, the second direction being
oriented orthogonally to the first direction.
14. The storage system according to claim 11, wherein, in the first
direction, the domain wall conductor has an extent and two magnetic
poles of the magnet arrangement have a center distance from each
other, wherein the extent is less than the center distance.
15. The storage system according to claim 11, wherein, in relation
to the first direction, a supporting magnet is arranged in addition
to the magnet arrangement.
Description
CROSS-REFERENCE TO PRIOR APPLICATIONS
[0001] Priority is claimed to German Patent Application No. DE 10
2019 218 351.4, filed on Nov. 27, 2019, the entire disclosure of
which is hereby incorporated by reference herein.
FIELD
[0002] The invention relates to a sensor element for storing
rotation or position information, for example for an angle or
length measuring device.
BACKGROUND
[0003] Angle measuring devices are used, for example, as rotary
encoders for determining the angular position of two machine parts
that are rotatable relative to each other. So-called multi-turn
angle measuring devices are frequently used for this purpose, by
means of which absolute position determination over many rotations
is possible.
[0004] Furthermore, length measuring devices are known in which a
linear displacement of two machine parts that are displaceable
relative to each other is measured. In particular, in the case of
length measuring devices with a comparatively large measurement
length, multiple linear scales or identical scales are often lined
up end to end. In the case of such length measuring devices,
absolute position determination is to be possible, if at all
possible over the entire measurement length.
[0005] Such measuring devices or measuring devices for electric
drives are frequently used for determining the relative movement or
the relative position of corresponding machine parts. In this case,
the position values generated are supplied to a subsequent
electronics system for driving the drives via a corresponding
interface arrangement.
[0006] EP 1 740 909 B1 describes a sensor element for a revolution
counter in which domain walls are formed, wherein the sensor
element has a specific spiral shape.
SUMMARY
[0007] In an embodiment, the present invention provides a sensor
element for storing rotation or position information. The sensor
element includes a substrate and a domain wall conductor arranged
on the substrate. A course of the domain wall conductor is of a
closed circumferential, continuous configuration without crossings.
The domain wall conductor comprises a first region having a
positive curvature and a second region having a negative
curvature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Embodiments of the present invention will be described in
even greater detail below based on the exemplary figures. The
present invention is not limited to the exemplary embodiments. All
features described and/or illustrated herein can be used alone or
combined in different combinations in embodiments of the present
invention. The features and advantages of various embodiments of
the present invention will become apparent by reading the following
detailed description with reference to the attached drawings which
illustrate the following:
[0009] FIG. 1 a plan view of a sensor element,
[0010] FIG. 2 a detailed view of a domain wall conductor,
[0011] FIG. 3 a magnet of a magnet arrangement,
[0012] FIG. 4 a plan view of the magnet arrangement on a carrier
plate,
[0013] FIG. 5 a plan view of the magnet arrangement with a
schematic representation of a magnetic field,
[0014] FIG. 6 a side view of a scale element in accordance with a
first exemplary embodiment,
[0015] FIG. 7 a top view of the scale element and the sensor
element in accordance with the first exemplary embodiment,
[0016] FIG. 8 a schematic view of the sensor element and the magnet
arrangement in a first relative position to each other,
[0017] FIG. 9 a partial view of the domain wall conductor with
domain walls marked in the first relative position,
[0018] FIG. 10 a schematic view of the sensor element and of the
magnet arrangement in a second relative position to each other,
[0019] FIG. 11 a partial view of the domain wall conductor with
domain walls marked in the second relative position,
[0020] FIG. 12 a schematic view of the sensor element and of the
magnet arrangement in a third relative position to each other,
[0021] FIG. 13 a partial view of the domain wall conductor with
domain walls marked in the third relative position,
[0022] FIG. 14 a schematic view of the sensor element and of the
magnet arrangement in a fourth relative position to each other,
[0023] FIG. 15 a partial view of the domain wall conductor with
domain walls marked in the fourth relative position,
[0024] FIG. 16 a schematic view of the sensor element and of the
magnet arrangement in a fifth relative position to each other,
[0025] FIG. 17 a partial view of the domain wall conductor with
domain walls marked in the fifth relative position,
[0026] FIG. 18 a schematic view of the sensor element and of the
magnet arrangement in a sixth relative position to each other,
[0027] FIG. 19 a partial view of the domain wall conductor with
domain walls marked in the sixth relative position,
[0028] FIG. 20 a view of the domain wall conductor with domain
walls marked in the further relative position during a second
rotation,
[0029] FIG. 21 a view of the domain wall conductor with domain
walls marked in the further relative position after completed
second rotation,
[0030] FIG. 22 a view of the domain wall conductor with domain
walls marked in the further relative position after completed third
rotation,
[0031] FIG. 23 a view of the domain wall conductor with domain
walls marked in the further relative position after completed
fourth rotation,
[0032] FIG. 24 a view of a sensor element with a further domain
wall conductor,
[0033] FIG. 25 a plan view of the scale element according to a
second exemplary embodiment,
[0034] FIG. 26 a plan view of the scale element according to a
third exemplary embodiment,
[0035] FIG. 27 a plan view of a sensor element according to the
fourth exemplary embodiment,
[0036] FIG. 28 a plan view of a magnet arrangement according to a
fourth exemplary embodiment,
[0037] FIG. 29 a side view of the magnet arrangement with the
sensor element according to the fourth exemplary embodiment.
DETAILED DESCRIPTION
[0038] In an embodiment, the present invention provides a sensor
element or a storage system which comprises a domain wall conductor
and which enables a robust operating performance in relation to
external influences and can be produced comparatively
economically.
[0039] The sensor element according to an embodiment of the present
invention for the in particular active storage of rotation or
position information comprises a domain wall conductor and a
substrate, wherein the course of the domain wall conductor on the
substrate is of a closed circumferential, continuous configuration
without crossings. Furthermore, the domain wall conductor has at
least one first region with a positive curvature and at least one
second region with a negative curvature.
[0040] The term "active storage" is to be understood to mean a
storage for which the relevant sensor element does not require any
auxiliary electrical energy.
[0041] In the context of the present invention, domain wall
conductors are in particular conductor tracks or conductor paths or
nanowires consisting of a magnetizable material. Information can be
stored in the domain wall conductors in the form of contrarily
magnetized regions (domains). The domains are separated by
so-called domain walls which can be displaced by magnetic fields,
wherein the positions of the domains change. To determine their
position, read-out elements are arranged, past which the domains or
domain walls are pushed. Domain wall conductors considered from a
functional perspective can therefore also be regarded as a type of
shift register.
[0042] The course of the domain wall conductor forms a continuous
curve and has neither a jump nor a peak, kink or any other point of
discontinuity. The term "continuous curve" is therefore to be
understood to mean a course of the domain wall conductor which is
embodied uniformly without abrupt changes in direction. Expressed
mathematically, the course of the domain wall conductor is thus
continuous and in particular differentiable over its entire length,
so that a unique tangent can thus be generated at each point on the
course of the domain wall conductor.
[0043] The crossing-free course of the domain wall conductor is to
be understood in particular to mean that the domain wall conductor
does not cross in its course, but also in different layers does not
cross over itself.
[0044] Curvature is to be understood to mean the change in
direction along the course of the domain wall conductor on the in
particular planar substrate. In the case of a straight course, the
curvature is equal to zero because the direction of progression
does not change. If the curvature is not equal to zero, the
curvature, signed in accordance with an orientation of the normal
bundle of the curve, can be defined for the course of the domain
wall conductor. The curvature is positive when it curves toward the
unit normal vector field and negative when it curves in the
opposite direction. For example, the first region with the positive
curvature may be referred to as a convex region, while the second
region with the negative curvature may then be referred to as a
concave region. Expressed mathematically, the course of the domain
wall conductor thus has in particular at least one inflection
point.
[0045] The sensor element advantageously comprises an in particular
planar substrate and the domain wall conductor is configured as a
conductor track on the substrate.
[0046] In an embodiment of the invention, the width of the domain
wall conductor is less than 1000 nm, in particular less than 500
nm, advantageously less than 300 nm.
[0047] The thickness or layer thickness of the domain wall
conductor is advantageously less than 200 nm, in particular less
than 150 nm, in particular less than 60 nm.
[0048] The substrate advantageously has a glass layer and/or a
silicon layer. In particular, when the substrate comprises a
silicon layer, the sensor element may be constructed as a part of a
CMOS chip.
[0049] In an advantageous embodiment, the sensor element
furthermore has read-out elements by means of which (at the
respective position of the read-out elements) the local
magnetization state of the domain wall conductor can be determined.
A magnetization state of the domain wall conductor can thus be
determined in each case by the read-out elements. The read-out
elements are arranged fixedly with respect to the domain wall
conductor.
[0050] In an embodiment of the invention, the domain wall conductor
is arranged in a layer between at least one of the read-out
elements and the substrate. Alternatively or additionally, at least
one of the read-out elements is arranged in a layer between the
substrate and the domain wall conductor.
[0051] The read-out elements are advantageously designed as GMR or
TMR sensors.
[0052] The sensor element may comprise a plurality of domain wall
conductors. In this case, the plurality of domain wall conductors
has different numbers of first regions or different numbers of
second regions. Thus, for example, the sensor element can have a
first domain wall conductor and a second domain wall conductor,
wherein the first domain wall conductor has a first number of first
regions and the second domain wall conductor has a second number of
first regions.
[0053] Advantageously the different numbers, that is to say the
number of the first regions of the first domain wall conductor and
the number of the first regions of the second domain wall
conductor, are coprime. As is generally known, the term coprime is
understood to mean that apart from one there is no natural number
that is a common divisor of the numbers in question (natural
numbers).
[0054] In another embodiment, the invention also comprises a
storage system with a sensor element and with a read-out element
and also a magnet arrangement. The magnet arrangement is movable in
a first direction relative to the domain wall conductor. This
causes a displacement of magnetic domains or of domain walls.
[0055] The magnetic field generated by the magnet arrangement is
advantageously configured asymmetrically with respect to an axis
which runs parallel to the first direction. This consideration
applies to any imaginary axis that runs parallel to the first
direction.
[0056] In an embodiment of the invention, the magnetic field
generated by the magnet arrangement is advantageously configured
symmetrically with respect to an axis which runs parallel to a
second direction. The second direction is oriented orthogonally to
the first direction.
[0057] The axis which runs parallel to the first direction and the
axis which runs parallel to a second direction lie in particular in
a plane which is oriented parallel to the substrate.
[0058] In an embodiment of the storage system, the magnet
arrangement is configured as a magnet array which has magnets whose
poles are arranged offset from each other in the first
direction.
[0059] Advantageously, two magnets offset relative to each other in
the first direction have a pole orientation rotated by 180.degree..
The magnets in question are thus arranged such that the connecting
line between the north pole and the south pole of one magnet is
parallel to the connecting line between the north pole and the
south pole of the other magnet, wherein the pole orientation of the
magnets is opposite. The offset magnets can therefore be referred
to as being arranged antiparallel to each other with regard to the
pole orientation.
[0060] In an embodiment of the storage system, the magnet array has
magnets whose poles are arranged offset from each other in a second
direction, wherein the second direction is oriented orthogonally
with respect to the first direction.
[0061] Advantageously, two magnets offset relative to each other in
the second direction and in particular adjacent magnets have a pole
orientation rotated by 180.degree..
[0062] The profile of the domain wall conductor is advantageously
configured axisymmetrically. In particular, the relevant axis of
symmetry can run parallel to the second direction or in the second
direction.
[0063] The domain wall conductor has an extension in the first
direction and two magnetic poles have a center distance, wherein
the extension is less than the center distance. To be understood in
particular here is the maximum extension of the domain wall
conductor in the first direction. The center distance can in
particular be the distance between the effective centers of the
magnets. For example, in the case of cylindrical rod magnets, the
center distance can be seen as the distance between the
longitudinal axes of the cylindrical rod magnets.
[0064] The storage system is designed in such a way that it has at
least two domain walls, wherein developments with four or more
domain walls can also be used.
[0065] FIG. 1 shows a sensor element comprising a domain wall
conductor 1 and a substrate 2, wherein the domain wall conductor 1
is applied to the substrate 2 in the form of a conductor track. In
the exemplary embodiment presented, the substrate 2 has a
mechanically supporting glass layer, wherein the substrate 2 is of
planar design. Alternatively, the substrate 2 may comprise a
silicon layer, wherein the sensor element may then be configured as
a part of a CMOS chip.
[0066] The domain wall conductor 1 comprises a soft magnetic
material, for example an Ni--Fe alloy. The domain wall conductor 1
comprises a first section 1.1 in which the domain wall conductor 1
runs in comparatively narrow loops and a second section 1.2 in
which the domain wall conductor 1 runs in an arc with a relatively
large radius. The first section 1.1 and the second section 2.2
adjoin one another directly, so that the course of the domain wall
conductor 1 is configured to be closed circumferentially. The
domain wall conductor 1 has a width X1 in a first direction x and
is configured symmetrically with respect to an axis C which is
oriented perpendicular to the first direction x and parallel to a
second direction y. In the exemplary embodiment presented, the
width X1 is 70 .mu.m, wherein the domain wall conductor 1 extends
over 5 mm in the second direction y.
[0067] A detail of the domain wall conductor 1 is shown in FIG. 2.
It can clearly be seen therein that the domain wall conductor 1 has
in its course a first region A with a positive curvature and a
second region B with a negative curvature. In other words, if one
were to follow the course of the domain wall conductor 1, one would
encounter both a section with a right curvature and a section with
a left curvature. In the course of the first section 1.1, a second
region B with a negative curvature follows a first region A with a
positive curvature and then once again a first region A etc.,
wherein in the exemplary embodiment presented regions with a
straight course of the domain wall conductor 1 are located between
the first regions A and the second regions B. In the second section
1.2, the sign of the curvature does not change. In the exemplary
embodiment presented, the curvature or the radius of curvature is
shown as constant.
[0068] According to FIG. 1, in a layer above the domain wall
conductor 1 read-out elements 7 are located, which can be GMR
sensors or TMR sensors, for example, with the aid of which the
magnetization state of the domain wall conductor 1 subjacent
thereto can be determined. Alternatively, the read-out elements 7
can also be arranged between the domain wall conductor 1 and the
substrate 2.
[0069] When a magnetic field moved relative to the domain wall
conductor 1 acts appropriately on the domain wall conductor 1,
domain walls W1, W2 will be displaced within the domain wall
conductor 1 or along the domain wall conductor 1. To form a
suitable magnetic field, a magnet arrangement 3 is used, which in
the embodiment presented is configured as a magnet array consisting
of a plurality of magnets 3.1 to 3.6. The magnet 3.1 is shown in
FIG. 3 by way of example for all magnets 3.1 to 3.6. In the
exemplary embodiment presented, all magnets 3.1 to 3.6 have an
identical design. Accordingly, the magnets 3.1 to 3.6 are designed
as cylindrical bodies, wherein the magnetic poles are arranged
along the longest axis of symmetry in the sense of a bar
magnet.
[0070] FIG. 4 shows a corresponding magnet arrangement 3. Compared
to the domain wall conductor 1 in FIG. 1 the magnet arrangement 3
is shown on a different scale. Magnets 3.1 to 3.6 are arranged in
different north-south orientation on a carrier 4 according to a
prespecified pattern. The magnets 3.1 to 3.6 can also be embedded
in the carrier 4.
[0071] In particular, magnets 3.1 to 3.3 can be arranged adjacent
to each other along the first direction x at a distance X2, wherein
adjacent magnets 3.1 and 3.2 or 3.2 and 3.3 have an opposite pole
orientation. Offset in a second direction y, further magnets 3.4 to
3.6 are lined up end to end in each case along the first direction
x likewise at a distance X2. In the exemplary embodiment presented,
the distance X2 is 0.33 mm. In the second direction y, the magnet
3.6 is offset relative to the remaining magnets 3.1 to 3.5.
[0072] A supporting magnetic field is provided in the direction x
on both sides adjacent to the magnet arrangement 3. The magnetic
fields can thus be represented in a simplified manner in FIG. 5,
wherein the arrows with a very thick line to the left and right of
the magnets 3.1 to 3.6 are intended to indicate the supporting
magnetic field. It can be seen in FIG. 5 that the directions of the
magnetic field lines change in such a way that turning or rotating
magnetic field lines are produced, wherein the rotation of the
magnetic field lines is present in each case about axes oriented in
a third direction z (see FIG. 3).
[0073] The magnetic field generated by the magnet arrangement 3 is
asymmetrical with respect to an axis Ax which runs parallel to the
first direction x. There is, in particular, no axis running
parallel to the first direction x which could represent an axis of
symmetry. In contrast, the magnetic field generated by the magnet
arrangement 3 is configured symmetrically with respect to an axis
Ay which runs parallel to the second direction y, so that an
axisymmetrical magnetic field is present with respect to the axis
Ay.
[0074] As an alternative to the construction shown here, bar
magnets can also lie in a plane which is oriented parallel to the
first direction x and parallel to the second direction y, so that
the north and south poles shown in FIG. 5 belong at least in part
to one and the same magnet, in particular to magnets lying in the
x-y plane.
[0075] The magnet arrangement 3 is usually fixed to a scale element
6 or to a material measure. In the first exemplary embodiment
according to FIGS. 6 and 7, the scale element 6 has a substantially
annular drum 6.1 as the body. The magnet arrangement 3 consisting
of magnets 3.1 to 3.6 and the carrier 4 is mounted on its external
circumference. In addition, the drum 6.1 has a supporting magnet
6.11 in the region of the external circumference. This can consist,
for example, of a layer of magnetizable material. The magnetization
is carried out in such a way that north pole and south pole are
arranged axially offset relative to each other. In the exemplary
embodiment presented, a fine scale 6.12 is applied
circumferentially on the drum 6.1 in the second direction y, that
is to say, displaced in the axial direction relative to the
supporting magnet. This can be decoded, for example, by an optical
scanning device, which is likewise accommodated in the housing 5.
Alternatively, the magnet arrangement 3 can also be arranged on the
internal circumference of a drum or of a hollow shaft.
[0076] Opposite the radial air gap, the sensor element, that is to
say, the domain wall conductor 1, is located with the substrate 2
within a housing 5. In the exemplary embodiment presented, the
housing 5 is in a fixed position, while the drum 6.1 is rotatably
mounted with the magnet arrangement 3 so that the magnet
arrangement 3 moves in the first direction x (or contrary thereto)
relative to the magnet arrangement 3 during rotation of the drum
6.1.
[0077] As a schematic diagram, FIG. 8 shows the magnet arrangement
3 and the domain wall conductor 1 in a first position relative to
each other. In this position, domain walls W1, W2 are in the
positions according to FIG. 9, wherein (as represented by the
symbols) the first domain wall W1 is a so-called head-to-head
domain wall and the second domain wall W2 is a so-called
tail-to-tail domain wall. If the domain wall conductor 1 together
with the substrate 2 moves relative to the magnet arrangement 3 in
the first direction x according to the arrow in FIG. 8, the domain
wall conductor 1 will be as to say guided by the rotating magnetic
field, as shown in FIG. 5. As a result, the positions of domain
walls W1, W2 will be displaced.
[0078] In FIG. 10 the domain wall conductor 1 is shown in a further
position, wherein the magnetic field is rotated relative to the
first position. Accordingly, domain walls W1, W2 have changed their
positions (FIG. 11).
[0079] Analogously, as a result of a further displacement of the
domain wall conductor 1 along the first direction x (FIGS. 12, 14,
16, 18), the positions of the domain walls W1, W2 are further
displaced (FIGS. 13, 15, 17, 19). The positions of the domain walls
W1, W2 in FIG. 19 include, for example, the information that the
drum 6.1 has completed a first rotation.
[0080] In the event of a further movement or rotation in the same
direction, the domain wall conductor 1 will remain in the influence
of the supporting magnetic field, so that the positions of the
domain walls W1, W2 then no longer change.
[0081] In the embodiment presented, the drum 6.1 is to rotate
further in the same direction x so that the domain wall conductor 1
comes back into the magnetic sphere of influence of the magnet
arrangement 3 in order to complete the second rotation. In FIG. 20,
the positions of the domain walls W1, W2 are shown during the
second rotation, wherein the domain wall conductor 1 with the
substrate 2 is located in a position according to FIG. 14 (however,
the drum 6.1 is then further rotated by 360.degree.. A displacement
of the domain walls W1, W2 over the length of the second section
1.2, in which the domain wall conductor 1 runs in an arc with a
relatively large radius, is achieved in particular by the magnetic
field of the magnet 3.6 offset in the second direction y or of the
supporting field. At the end of the second rotation, when the
domain wall conductor 1 is in a position according to FIG. 18
(relative to the situation in FIG. 18, the drum 6.1 is further
rotated by 360.degree., the domain walls W1, W2 will have assumed
positions according to FIG. 21.
[0082] FIG. 22 shows the positions of the domain walls W1, W2 after
a third rotation of the drum 6.1. In this state, the domain wall
conductor 1 is in a position according to FIG. 18 (however, the
drum 6.1 is then further rotated by 720.degree..
[0083] Consequently, the positions of the domain walls W1, W2 in
FIG. 23 show that the drum 6.1 has completed a fourth rotation
(position of the drum 6.1 is further rotated as in FIG. 18, but
rotated by 1080.degree.. The positions of the domain walls W1, W2
correspond to those of the initial state.
[0084] After each passing-by of the magnet arrangement 3 or after
each rotation of the drum 6.1, the domain wall W1 will thus have
moved further to an adjacent first region A of the domain wall
conductor 1 in each case. Correspondingly, after each rotation, the
domain wall W2 will have moved further to an adjacent second region
B of the domain wall conductor 1 or be located in the second
section 1.2 in which the domain wall conductor 1 runs in an arc
with a relatively large radius.
[0085] The directions of magnetization within sections of the
domain wall conductor 1 and thus the rough positions of the domain
walls W1, W2 can be detected by the read-out elements 7. In this
way, a count of rotations or storage of the rotation information is
possible, even if no auxiliary energy is usable. This is important,
for example, if, in the event of a power failure, a shaft is moved
for instance by weight load. Other than that the domain walls W1,
W2 are displaced depending on the direction of rotation, so that
the sensor element can be used reliably in applications which
permit both directions of rotation.
[0086] In order to increase the number of countable rotations, a
plurality of domain wall conductors 1 may be provided, as is shown
in simplified form in FIG. 24. In this case, it is advantageous if
the plurality of domain wall conductors 1 have different numbers of
first sections 1.1, in particular have different numbers of first
regions A or have different numbers of second regions B. If a
plurality of domain wall conductors 1 are used, it is advantageous
if the numbers of the first regions A are in particular coprime.
The plurality of domain wall conductors 1 can be offset relative to
each other in the first direction x or interleaved with each other.
In FIG. 24, the domain wall conductors are configured in such a way
that they have four and five first regions A, wherein domain wall
conductors with comparatively small numbers of first regions are
shown in FIG. 24 for the sake of clarity. In practice, it is
appropriate to use domain wall conductors with more than just four
first regions. For example, four domain wall conductors can be used
with 7, 9, 11, 13 first regions, so that 9009
(7.times.9.times.11.times.13) rotations would then be
countable.
[0087] For the functioning of the storage system, it is important
that, during the passing-by of the magnet arrangement 3 along the
first direction x, a magnetic field is applied to the domain wall
conductor 1, the direction of which changes as a function of the x
position. In particular, turning or rotating magnetic field lines
or magnetic field directions are present here during the
passing-by. Magnetic field lines on one side of the axis Ax (FIG.
5) have an opposite sense of rotation during the passing-by
(without change in direction) compared to magnetic field lines on
the other side of the one axis Ax.
[0088] FIG. 25 shows a second exemplary embodiment. Here, the
magnet arrangement 3 is fixed to an end face of a drum 6.2. The
sensor element is arranged with an axial offset, that is to say,
with an air gap which has an axial extent. With each passing-by of
the magnet arrangement 3 at the sensor element the rotation
information is updated, wherein domain walls W1, W2 are displaced
as a function of the direction of rotation.
[0089] A third exemplary embodiment is explained with reference to
FIG. 26. In this exemplary embodiment, the sensor element is used
in connection with a linear scale 6.3. In the exemplary embodiment
presented, this scale 6.3 comprises a first scale section 6.31 and
a second scale section 6.32. The first scale section 6.31 and the
second scale section 6.32 are lined up end to end along the first
direction x, so that a comparatively large measuring length can be
achieved. In practice, it is also perfectly possible for more than
just two scale sections to be lined up end to end. The first scale
section 6.31 comprises a supporting magnet 6.311 and the second
scale section 6.32 comprises a supporting magnet 6.321. The magnet
arrangements 3 are provided laterally in the first direction x
offset in relation to the supporting magnets 6.311, 6.321. A
scanning head has a sensor element with the domain wall conductor 1
and with a scanning device of an incremental track 6.313, 6.323 and
of an absolute track 6.312, 6.322 (the incremental track 6.313,
6.323 and the absolute track 6.312, 6.322 extend over the two scale
sections 6.31, 6.32). By means of the sensor element, it is
possible to store position information so that it is possible to
determine which of the scale sections 6.31, 6.32 is currently being
scanned.
[0090] A fourth exemplary embodiment can be explained with
reference to FIGS. 27 to 29. FIG. 27 shows a sensor element which
has a domain wall conductor 1' which is modified with respect to
the preceding exemplary embodiments and which runs around a central
center of rotation (representation of read-out elements has been
omitted in the figure). For displacing the domain walls, a magnet
arrangement 3' is used, for example, which, as shown in FIG. 28,
comprises two disk-shaped magnets 3.1', 3.2', which, in particular,
have different diameters. The magnets 3.1', 3.2' have diametrical
magnetization, so that the poles are arranged radially offset from
one another. The magnets 3.1', 3.2' are arranged offset relative to
one another along an axis G (that is to say axially), wherein their
pole orientations are skewed 180.degree. degrees with respect to
the axis G. The magnets 3.1', 3.2' themselves are installed fixedly
relative to one another in the corresponding storage system and
thus cannot skew relative to each other or displace in any way
relative to each other. As shown in FIG. 29, the distance g1
between the domain wall conductor 1' or the substrate 2, and the
magnet 3.1' with the larger diameter is greater than the distance
g2 between the domain wall conductor 1' or the substrate 2, and the
magnet 3.2' with the smaller diameter (g1>g2). In this way, a
magnetic field can be generated by means of which a suitable
displacement of domain walls is achieved when the domain wall
conductor 1' or the substrate 2 rotates about the axis G relative
to the magnet arrangement 3' or moves along the first direction x'
relative to the magnet arrangement 3'. It is thereby possible to
count the number of rotations of the substrate 2 relative to the
magnet arrangement 3'.
[0091] While embodiments of the invention have been illustrated and
described in detail in the drawings and foregoing description, such
illustration and description are to be considered illustrative or
exemplary and not restrictive. It will be understood that changes
and modifications may be made by those of ordinary skill within the
scope of the following claims. In particular, the present invention
covers further embodiments with any combination of features from
different embodiments described above and below. Additionally,
statements made herein characterizing the invention refer to an
embodiment of the invention and not necessarily all
embodiments.
[0092] The terms used in the claims should be construed to have the
broadest reasonable interpretation consistent with the foregoing
description. For example, the use of the article "a" or "the" in
introducing an element should not be interpreted as being exclusive
of a plurality of elements. Likewise, the recitation of "or" should
be interpreted as being inclusive, such that the recitation of "A
or B" is not exclusive of "A and B," unless it is clear from the
context or the foregoing description that only one of A and B is
intended. Further, the recitation of "at least one of A, B and C"
should be interpreted as one or more of a group of elements
consisting of A, B and C, and should not be interpreted as
requiring at least one of each of the listed elements A, B and C,
regardless of whether A, B and C are related as categories or
otherwise. Moreover, the recitation of "A, B and/or C" or "at least
one of A, B or C" should be interpreted as including any singular
entity from the listed elements, e.g., A, any subset from the
listed elements, e.g., A and B, or the entire list of elements A, B
and C.
* * * * *